The construction of a magneto inductive, flow measuring device of the field of the invention with modular construction composed of a coil system with a pole shoe and corresponding flux return sheets is described, for example, in German patent DE 10 2011 079 351.8. Such modular constructions are attractive due, among other things, to their simple mounting around the measuring tube.
Known are magnet systems, which provide a dividing of a coil arrangement, but use a different structural construction and produce different magnetic fields. For example, U.S. Pat. No. 4,726,236 B discloses a magnet system with a cylindrical core and a coil arrangement composed of a total of four coils wound on the core. In such case, the coil core is embodied to go all the way around. German patent DE 1 648 143 discloses coil pairs for producing a uniform magnetic field. Also in this case, the coil core is composed of an encircling ring with inwardly leading, pencil-shaped structures, around which the coils are arranged. DE 1 911 556 discloses a multi-coil arrangement using flat coils for lessening the dimensions of the coil arrangement. All these documents, however, show no modular construction with pole shoes and flux return sheets.